Towards Reagents for Bimetallic Activation Reactions: Polyhydride Complexes with Ru₂H₃, Ru₂ZnH₆, and Cu₂Ru₂H₆ Cores

Abstract

The utility of the fac-[RuH 3 (PR 3 ) 3 ]anion (R = Ph, C 6 H 4 -4-Me) for the preparation of new oligonuclear transition metal polyhydrides has been examined. The lithium salts [Li(thf) x {Ru(μ-H) 3 (PPh 3 ) 3 }] {1: R = Ph, x = 3; 1Ј: R = C 6 H 4 -4-Me (Tol), x = 2.5} react with [Cp*RuCl] 4 (Cp* = C 5 Me 5 ), ZnCl 2 , and CuCl(SMe 2 ) to form new oligonuclear polyhydrido complexes. The compounds [Cp*Ru(μ-H) 3 Ru(PR 3 ) 3 ] (2: R = Ph, 2Ј: R = Tol), [Zn{Ru(μ-H) 3 (PPh 3 ) 3 } 2 ] (3), and [a]

Ketone Hydrogenation with Iridium Complexes with “non N–H” Ligands: The Key Role of the Strong Base

“…The less stable geometry can be described as a pentagonal bipyramid with two axial and one equatorial PPh 3 ligands (4.3 kcal/mol higher than the minimum). The anionic trihydride complex [RuH 3 (PPh 3 ) 3 ] − has a regular octahedral geometry with a fac arrangement of the hydrides and PPh 3 ligands, as in the experimentally determined structures of [K­(18-crown-6)]­[RuH 3 (PPh 3 ) 3 ] and [Li­(THF) 3 ]­[RuH 3 (PPh 3 ) 3 ] …”

“…The anionic trihydride complex [RuH 3 (PPh 3 ) 3 ] − has a regular octahedral geometry with a fac arrangement of the hydrides and PPh 3 ligands, as in the experimentally determined structures of [K(18-crown-6)][RuH 3 (PPh 3 ) 3 ] 99 and [Li-(THF) 3 ][RuH 3 (PPh 3 ) 3 ]. 100 Using the same base and conjugate acid models also employed to calculate the deprotonation energetics of the iridium system, namely the [MeO(MeOH) 5 ] − and (MeOH) 6 clusters, the deprotonation of the tetrahydride complex was found nearly thermoneutral (−0.7 kcal/mol). This result is in good agreement with the experimental evidence of an equilibrated process for the [RuH 3 (PPh 3 ) 3 ] − /[RuH 2 (H 2 )-(PPh 3 ) 3 ] system (the experimental study used cyclohexanol in THF-D 8 ) 95 and confirms that the Ir system has greater tendency to be anionic in basic alcohol relative to the Pez/ Halpern Ru system.…”

Activation of H2 over the Ru−Zn Bond in the Transition Metal−Lewis Acid Heterobimetallic Species [Ru(IPr)2(CO)ZnEt]+

“…Although examples of {M­(H) n Zn} complexes exist for M = Ru, as well as for other late TMs, these all result from metal hydride precursors, and, to the best of our knowledge, formation via bimetallic M-Zn cleavage of H 2 has no precedent. , We have therefore used DFT calculations to study the formation of 2 as well as its onward reactivity with H 2 to 3 and 4 . Figure indicates that the initial addition of ZnEt 2 to 1 forms an intermediate I­(1-2)­1 at −12.3 kcal/mol in which the {Ru-Zn} moiety is bridged by both a hydride and an ethyl ligand; the latter also engages in a β-agostic interaction with the Ru center.…”

Reversible Oxidative Addition of Zinc Hydride at a Gallium(I)‐Centre: Labile Mono‐ and Bis(hydridogallyl)zinc Complexes

“…Although the TM‐mediated chemistry of diorganozinc reagents ZnR 2 has been investigated in detail, [17] analogous low‐valent MG‐mediated organozinc reactivity remains underexplored. [ 14f , 18 ] Examples of zinc‐containing heterometallic hydride complexes are numerous,[ 7f , 7h , 7k , 7m , 7n , 8b , 17g , 17j , 19 ] but we are unaware of any that derive directly from the parent dihydride [ZnH 2 ] n . This lacuna is unsurprising given that polymeric [ZnH 2 ] n is insoluble in organic solvents, thermally sensitive, and challenging to synthesise in an analytically pure form.…”